Distinct Resistance Research Articles

Mutational signature analysis predicts bacterial hypermutation and multidrug resistance

Bacteria of clinical importance, such as Pseudomonas aeruginosa, can become hypermutators upon loss of DNA mismatch repair (MMR) and are clinically correlated with high rates of multidrug resistance (MDR). Here, we demonstrate that hypermutated MMR-deficient P. aeruginosa has a unique mutational signature and rapidly acquires MDR upon repeated exposure to first-line or last-resort antibiotics. MDR acquisition was irrespective of drug class and instead arose through common resistance mechanisms shared between the initial and secondary drugs. Rational combinations of drugs having distinct resistance mechanisms prevented MDR acquisition in hypermutated MMR-deficient P. aeruginosa. Mutational signature analysis of P. aeruginosa across different human disease contexts identified appreciable quantities of MMR-deficient clinical isolates that were already MDR or prone to future MDR acquisition. Mutational signature analysis of patient samples is a promising diagnostic tool that may predict MDR and guide precision-based medical care.

Physiological and biochemical study of four new maize lines (Zea mays l.) In Daloa, Cote D Ivoire

Maize (Zea mays L.) is a cereal belonging to the Poaceae family that adapts to a variety of ecological conditions. However, increasing climate change is leading to numerous abiotic and biotic stresses that are reducing its production. Faced with these challenges, it is becoming essential to develop new maize varieties with characteristics that can adapt to changing climatic conditions. The study focused on the physiological and biochemical characterisation of four maize lines derived from the EV8728 variety irradiated with gamma radiation after 6 generations of self-fertilisation. These lines were compared with the unirradiated parent variety EV8728. The results showed a significant effect on all the parameters assessed. At physiological level, chlorophyll (a), (b) and total contents were higher in the non-irradiated EV8728 variety and line S03. Biochemically, phenolic compound and total sugar levels were highest in lines S20 and S24. In terms of enzymatic activity, lines S03 and S76A showed higher levels of polyphenol oxidase (PPO). Lines S20 and S24 showed higher levels of peroxidase (POD) and line S76A accumulated more catalase (CAT) than the witness. These biochemical variations probably reflect distinct adaptation and resistance mechanisms within these lines.

Gut Microbial Composition and Antibiotic Resistance Profiles in Dairy Calves with Diarrhea

Calf diarrhea is a prevalent and significant health issue in dairy farming, severely impacting feed intake, weight gain, and survival rates in young calves. This study aimed to investigate the microbial composition and antibiotic resistance profiles of diarrheic calves to provide insights into the epidemiology and management of the condition. The prevalence of diarrhea in 1685 calves was analyzed. Rectal fecal samples were collected from five healthy and five diarrheic Holstein calves on a large dairy farm in Shaanxi Province, China. High-throughput 16S-rRNA sequencing and PCR were utilized for microbial and resistance gene analysis. In 2023, the overall diarrhea rate among 1685 calves was 9.08%, with a significantly higher diarrhea rate during the suckling period (8.13%) compared to the post-weaning period (0.95%) (p < 0.001). No differences in species diversity and richness were detected among the different groups. However, LEfSe analysis identified six genera (Eubacterium, Eubacteriaceae, Prevotella, Comamonadaceae, Comamonas, and Firmicutes) significantly enriched in diarrheic calves compared to healthy ones (LDA scores > 2, p < 0.05). Additionally, antibiotic resistance genes for quinolones, β-lactams, chloramphenicol, tetracyclines, and aminoglycosides were detected, with significantly higher prevalence in diarrheic calves. These findings demonstrate distinct microbial and antibiotic resistance profiles between healthy and diarrheic calves, emphasizing the importance of microbial management in controlling calf diarrhea.

Genetic basis of resistance in hosts facing alternative infection strategies by a virulent bacterial pathogen.

Having alternative infection routes is thought to help parasites circumvent host resistance, provided that these routes are associated with different host resistance loci. This study tests this postulate by examining whether alternate infection routes of the parasite Pasteuria ramosa are linked to distinct resistance loci in its crustacean host, Daphnia magna. We focus on the P. ramosa isolate P15, which can attach and penetrate the host through either the hindgut or the foregut. Using a global panel of 174 D. magna genotypes supplemented with breeding experiments, we analyzed resistance patterns for each of these infection routes. Our findings confirm our hypothesis: in D. magna, hindgut attachment is determined by the D locus, while foregut attachment is controlled by a newly identified G locus. We established a gene model for the G locus that indicated Mendelian segregation and epistatic interaction with at least one other resistance locus for P. ramosa, the C locus. Using genomic Pool-sequencing data, we localized the G locus within a known Pasteuria Resistance Complex on chromosome 4 of D. magna, whereas the D locus is on chromosome 7. Two candidate genes for the G locus, belonging to the Glycosyltransferase gene family, were identified. Our study sheds new light on host-parasite coevolution and enhances our understanding of how parasites evolve infection strategies.

Realizing multi-level phase-change storage by monatomic antimony

With the growing need for extensive data storage, enhancing the storage density of nonvolatile memory technologies presents a significant challenge for commercial applications. This study explores the use of monatomic antimony (Sb) in multi-level phase-change storage, leveraging its thickness-dependent crystallization behavior. We optimized nanoscale Sb films capped with a 4-nm SiO2 layer, which exhibit excellent amorphous thermal stability. The crystallization temperature ranges from 165 to 245 °C as the film thickness decreases from 5 to 3 nm. These optimized films were then assembled into a multilayer structure to achieve multi-level phase-change storage. A typical multilayer film consisting of three Sb layers was fabricated as phase-change random access memory (PCRAM), demonstrating four distinct resistance states with a large on/off ratio (∼102) and significant variation in operation voltage (∼0.5 V). This rapid, reversible, and low-energy multi-level storage was achieved using an electrical pulse as short as 20 ns at low voltages of 1.0, 2.1, 3.0, and 3.6 V for the first, second, and third SET operation, and RESET operation, respectively. The multi-level storage capability, enabled by segregation-free Sb with enhanced thermal stability through nano-confinement effects, offers a promising pathway toward high-density PCRAM suitable for large-scale neuromorphic computing.

ALDH3A1-mediated detoxification of reactive aldehydes contributes to distinct muscle responses to denervation and Amyotrophic Lateral Sclerosis progression.

Different muscles exhibit varied susceptibility to degeneration in Amyotrophic Lateral Sclerosis (ALS), a fatal neuromuscular disorder. Extraocular muscles (EOMs) are particularly resistant to ALS progression and exploring the underlying molecular nature may deliver great therapeutic value. Reactive aldehyde 4-hydroxynonenal (HNE) is implicated in ALS pathogenesis and ALDH3A1 is an inactivation-resistant intracellular detoxifier of 4-HNE protecting eyes against UV-induced oxidative stress. Here we detected prominently higher levels of ALDH3A1 in mouse EOMs than other muscles under normal physiological conditions. In an ALS mouse model (hSOD1G93A) reaching end-stage, ALDH3A1 expression was sustained at high level in EOMs, whereas substantial upregulation of ALDH3A1 occurred in soleus and diaphragm. The upregulation was less pronounced in extensor digitorum longus (EDL) muscle, which endured the most severe pathological remodeling as demonstrated by unparalleled upregulation of a denervation marker ANKRD1 expression. Interestingly, sciatic nerve transection in wildtype mice induced ALDH3A1 and ANKRD1 expression in an inverse manner over muscle type and time. Adeno-associated virus enforced overexpression of ALDH3A1 protected myotubes from 4-HNE-induced DNA fragmentation, plasma membrane leakage and restored MG53-mediated membrane repair. Our data indicate that ALDH3A1 may contribute to distinct muscle resistance to ALS through detoxifying reactive aldehydes.

Molecular characteristics, clonal transmission, and risk factors of Clostridioides difficile among hospitalized patients in a tertiary hospital in Ningbo, China.

Nosocomial transmission of Clostridioides difficile infection (CDI) has been documented in Ningbo, China. However, data on molecular characteristics, clonal transmission, and risk factors of CDI in this region remain limited. A cross-sectional study enrolled hospitalized patients with diarrhea during September to November 2021. Stool samples from all patients were tested for C. difficile, and isolated strains underwent toxin gene identification, genotyping, and antibiotic susceptibility testing. Whole-genome sequencing and epidemiological variables were analyzed in patients infected with C. difficile strains of the same sequence types (STs) to identify nosocomial transmission and risk factors for CDI. Of the 907 investigated patients, 115 (12.7%) had microbiologically proven CDI, as their diarrhea was associated with toxigenic C. difficile strains, which comprised 106 A+B+CDT-, 3 A-B+CDT-, and 6 A+B+CDT+. Predominant genotypes (ST2, ST3, ST35, and ST54) exhibited distinct antibiotic resistance patterns. ST54 strains showed higher resistance to erythromycin (100%) but lower resistance to moxifloxacin (18.2%) and gatifloxacin (18.2%) (χ 2 = 10.24-16.65, p < 0.05). ST35 strains exhibited higher resistance to ciprofloxacin (66.7%) and tetracycline (33.3%) than other STs (χ 2 = 13.30-20.19, p < 0.05). Genomic and epidemiological analysis revealed two nosocomial clonal transmission events caused by 5 ST35 strains (with ≤2 single nucleotide polymorphism differences), elucidating clonal transmission among different floors and buildings within the hospital. Prolonged hospitalization (> 10 days) (odds ratio [95% confidence interval], 1.76 [1.05-2.93]) and penicillin-class antibiotics (1.69 [1.11-2.58]) were risk factors for CDI, with the latter being an independent risk factor (1.57 [1.02-2.42]). For C. difficile ST35 infection, intensive care unit (12.00 [2.77-52.05]) and neurology departments (8.08 [1.46-44.65]) admissions were risk factors, with the latter as an independent risk factor (1.56 [1.01-2.40]). Multiple C. difficile genotypes with varied antibiotic resistance patterns circulated in Ningbo, with ST35 causing nosocomial clonal transmission among different floors and buildings within the hospital. These findings and the identified risk factors necessitate enhanced surveillance and infection control in the region.

Resistome phylodynamics of multidrug-resistant Shigella isolated from diarrheal patients.

Multi-drug resistance (MDR) in Shigella continues to pose a significant public health challenge, particularly in developing countries. Recent advances in genomics strengthen the surveillance of MDR-pathogens and antimicrobial resistance (AMR) mediators. However, genome-based investigations into resistome dynamics in Shigella are limited, specifically in Bangladesh. Therefore, we investigated MDR-Shigella resistomes to evaluate their AMR transmission and phylodynamics. Clinical Shigella strains were screened for MDR phenotypes through susceptibility tests against 28 antibiotics from 10 different classes. Whole-genome sequencing (WGS) and bioinformatics approaches were performed to unveil the resistome dynamics: >500 global plasmid entities and >1,000 plasmid-mediated resistance gene clusters from global databases were included in this study. We identified 28 distinct antimicrobial resistance genes (ARGs) from nine antibiotic classes, with 75% originating from plasmids. Notably, two conjugative MDR plasmids included nearly all potential ARGs, conferring resistance to first-line drugs for shigellosis. Two third-generation cephalosporin-resistant [wubC-blaCTX-M-15-ISEcp1 and blaTEM-1] and two macrolide-resistant mobile genomic islands (GIs) [mphA-mrx-mph(R)A-IS6100 and mphE-msrE-IS482-IS6] had emerged in Shigella in Bangladesh. In addition, trimethoprim-aminoglycoside-streptothricin-sulfonamide-resistant dfrA1-sat1-aadA1 and aph3-dfrA14-aph6-sul2 were in conjugative plasmids in Bangladesh. The MDR plasmids and resistant GIs were phylogenetically relevant to Europe, USA, or China-derived isolates, indicating carry-over of the emerging ARGs from heavily industrialized countries and MSM-burdened (men who have sex with men) populations. The global burden of resistance GIs has increased sharply, especially after 2014. Emerging resistance mediators were most frequent (>80%) in human-associated Escherichia coli and Klebsiella pneumoniae. We infer ARGs horizontally propagate among Enteropathogens: informing treatment strategies and supporting policymakers in strengthening AMR-containment efforts utilizing the phylodynamics network.IMPORTANCEThe world is suffering from a high burden of MDR enteropathogens. Healthcare providers in low- and middle-income countries (LMICs) often face trouble finding effective drugs among the many antibiotics introduced in diarrheal treatment. Resistance-mediated drug inactivation is more rapid than the advent of new antimicrobials, leaving enteritis treatment on the edge. In Bangladesh, where one-third of users are self-prescribing antibiotics and thousands are dying due to resistance-related treatment failure, phylogenomic evidence of AMR transmission root is scarce. Therefore, investigating the resistomes of MDR-Shigella, the leading cause of diarrheal deaths in Bangladesh, is crucial. We identified several emerging resistance mediators and their phylogenetic links to global entities, which is significant for improving shigellosis treatment and enhancing AMR containment strategies. Understanding the MDR mechanism in Shigella will help physicians choose effective drugs and anticipate resistance-mediated changes in treatment approaches; the spatiotemporal phylodynamics of AMR mediators aid policymakers in setting effective checkpoints in the AMR transmission network.

Distinct interspecies thermal resistance strategies exhibited by euplanktonic, tychoplanktonic and benthic diatoms under marine heatwaves

Extreme climate events, such as marine heatwaves (MHWs), are expected to occur more frequently and intensely in the future, resulting in a substantial impact on marine life. The way that diatoms respond to MHWs may have crucial effects on global primary production and biogeochemical cycles. Euplanktonic diatoms appear to benefit from MHWs directly, but this phenomenon needs an explanation. As concerns tychoplanktonic and benthic diatoms, no studies have been addressed on their thermal response strategies. To address this, we investigated the responses and underlying mechanisms of three typical growth forms of diatoms, Pseudo-nitzschia multiseries (euplanktonic), Paralia guyana (tychoplanktonic) and Navicula avium (benthic), under heat stress by combining a growth experiment with transcriptomic analysis. Our results showed that the physiological responses of diatoms to MHWs and underlying molecular mechanisms are largely related to their growth forms. The euplanktonic diatom was first depressed, but then had a distinct increase in the growth rate accompanied by inducing zeatin and unsaturated fatty acid biosynthesis and repressing substance assimilation and energy metabolism. Contrarily, the benthic diatom showed elevated substance and energy demands for macromolecules accumulation by reducing cell division and increasing photosynthesis and nitrogen assimilation. The tychoplanktonic diatom exhibited higher physiological plasticity to maintain growth and cellular homeostasis. Our results indicate the increased rate of cell division in euplanktonic diatoms under heat stress is likely an emergency response strategy promoting diatom dispersal for survival, but at the cost of disturbances of metabolic balance.

Comparative analysis of stomatal characteristics and Erysiphe necator (Schw.) Burrill resistance in diverse Vitis sp.

Powdery mildew caused by Erysiphe necator poses a major challenge for grapevine cultivation. This study investigates how stomatal and structural traits influence resistance to this pathogen across diverse Vitis genotypes. Microscopic analysis revealed significant variations in stomatal characteristics. The sunken stomata were observed in V. parviflora, V. jacquemontii, V. rupestris x V. berlandieri (110 Richter) and V. rupestris (St. George) with lower stomatal density. Genotypes with raised stomata had larger stomatal complex areas. Following inoculation with E. necator (accession No. 52218), the Vitis genotypes showed a distinct resistance response. Susceptible V. vinifera genotypes had high pathogen penetration rates, with 71 % of infection attempts forming haustoria. In contrast, V. parviflora, V. jacquemontii, and hybrids such as V. rupestris x V. berlandieri and V. riparia x V. cinerea exhibited programmed cell death (PCD)-mediated resistance, arresting up to 55 per cent of penetration attempts limiting hyphal growth. Cryo-SEM images further indicated sparse fungal growth on the resistant genotypes. The genotype V. parviflora possessed dense trichomes and long wax stripes along the epidermal cells covering leaf veins on the adaxial leaf surface, thus causing a physical barrier against the pathogen. Comparative analyses showed that callose deposition and epicuticular wax significantly contributed to early-stage pathogen defence, while reactive oxygen species and rapid PCD activation triggered hypersensitive responses, enhancing wax deposition and active PCD responses are critical for Vitis sp. resistance to powdery mildew, offering valuable insights for breeding programmes.

Environmental enrichment reduces adgrl3.1-Related anxiety and attention deficits but not impulsivity

Environmental factors play a role in the development and severity of neuropsychiatric disorders. Externalizing disorders are characterized by disruptive, impulsive, and often aggressive behaviors, including difficulties with self-control, rule-breaking, and a tendency to act out in ways that may harm oneself or others. Externalizing disorders frequently co-occur with internalizing disorders, such as anxiety. Individuals experiencing both externalizing/internalizing disorders are often among the most likely to seek healthcare services, as this co-occurrence is associated with more severe symptomatology and greater functional impairment. Here, we investigated the impact of environmental enrichment (EE) on adgrl3.1, a gene associated with impulsivity and attention deficits in zebrafish (Danio rerio). This gene encodes a receptor involved in cell adhesion and signaling and has been linked to susceptibility to externalizing disorders. Zebrafish were reared in either standard or enriched environments (from 15 days-post fertilization), and attention, impulsivity, and anxiety-related phenotypes were assessed at adult stages (4 months-post fertilization) using the open field test and a 5-choice serial reaction time task. EE mitigated anxiety-related behaviors in adgrl3.1 knockouts, normalizing locomotor patterns and decreasing thigmotaxis. Although attention deficits were reduced in adgrl3.1-/- fish reared in EE, impulsive behaviors were not. Together, these findings suggest that while environmental enrichment (EE) mitigates externalizing and internalizing symptoms in adgrl3.1 mutants, impulsivity remains less responsive to EE used in this study, indicating its distinct resistance to modulation.

Genome-wide association of an organic naked barley diversity panel identified quantitative trait loci for disease resistance.

Foliar fungal diseases are a major limitation in organic naked barley (Hordeum vulgare L.) production. The lack of conventional fungicides in organic systems increases reliance on genetic resistance. We evaluated the severity of barley stripe rust (Puccinia striiformis f.sp. hordei Westend), leaf rust (Puccina hordei sp. hordei), spot blotch (Cochliobolus sativus, anamorph Bipolaris sorokiniana (S. Ito & Kurib.) Drechsler ex Dastur), and scald (Rhynchosporium commune Zaffarano, McDonald and Linde sp. nov) on a naked barley diversity panel of 350 genotypes grown in 13 environments to identify quantitative trait loci associated with disease resistance. Genome-wide association analyses across and within environments found 10 marker trait associations for barley stripe rust, four marker trait associations for leaf rust, one marker trait association for scald, and five marker trait associations for spot blotch. Structure analysis identified six Ward groups based on genotypic diversity. Resistance to susceptible allele ratios were high for stripe rust and spot blotch, moderate for leaf rust, and low for scald. Combined phenotypic analysis values for each disease overlayed by a principal component analysis found distinct resistance and susceptibility patterns for barley stripe rust and scald. Most significant marker trait associations were previously identified in the literature, providing confirmation and potential new sources of disease resistance for genetic improvement of naked barley germplasm.

Gut Microbiome Characterisation of Chrysomya megacephala: Isolation, Identification, Antibiotic Profiling, and Initial Documentation of Leclercia adecarboxylata from the Fly

Chrysomya megacephala, known for its vector potential, harbors a diverse microbiota crucial in understanding disease transmission dynamics. Herein, we report the first documentation of Leclercia adecarboxylata isolated from C. megacephala. L. adecarboxylata is an Enterobacteriaceae, gram-negative bacillus that cause infections in human and animals. Additionally, we have reported the presence of Pseudomonas aeruginosa and Enterococcus faecalis from C. megacepahala. The study carried out the antibiotic profiling and hemolytic assays, which revealed distinct resistance patterns and virulence characteristics, shedding light on potential public health implications. L. adecarboxylata, Pseudomonas aeruginosa and Enterococcus faecalis showed positive result for hemolysis and in terms of antibiotic resistance P. aeruginosa strains showed resistance to Amoxicillin, Ampicillin and Tetracycline while, E. faecalis showed resistance towards Streptomycin and Tetracycline. However, L. adecarboxylata showed sensitivity to all antibiotics. This study was conducted from Kozhikode, Kerala, India, and this is the first of its kind of study from the region to analyse the vector potential of C. megacephala. These findings underscore the significance of comprehensive microbiological investigations in vector-borne disease surveillance and management strategies.

Cytogenetic and molecular identification of novel wheat-Elymus sibiricus addition lines with resistance to leaf rust and the presence of leaf pubescence trait.

Emerging new races of leaf rust (Puccinia triticina Eriks) are threatening global wheat (Triticum aestivum L.) production. Identifying additional resistance genes from all available gene pools is crucial to expanding wheat resistance to these virulent leaf rust races. Siberian wild rye (Elymus sibiricus L.) possesses numerous beneficial traits that can be valuable in wheat improvement. Three new wheat-E. sibiricus addition lines, O27-2 (BC8), O27-3 (BC12) and O193-3 (BC12), were developed through a backcrossing scheme in this study, using leaf rust field evaluations, molecular marker assays and cytogenetic analysis. These three lines were derived from progeny of the bread wheat cultivar 'Obriy' (2n = 6x = 42, AABBDD) and partial octoploid amphiploid wheat-E. sibiricus (2n = 8x = 56, AABBDDStSt). The lines (O27-2, O27-3 and O193-3) demonstrated strong specific leaf pubescence (hairiness) and resistance at the adult stage to a local population of leaf rust races. The response to leaf rust in these three lines significantly differed from that of the Lr24 gene, providing evidence for a distinct resistance mechanism associated with the 3St chromosome. This study is the first to report the transfer of an E. sibiricus chromosome into wheat that confers leaf rust resistance. Molecular marker analysis and genomic in situ hybridization confirmed that lines O27-2, O27-3 and O193-3 each possess one pair of E. sibiricus 3St chromosomes. The resistance gene was determined to be on the additional alien chromosome in these lines. Molecular markers (Xwmc221, Lr29F18, Sr24/Lr24) confirmed that the lines O27-2, O27-3, and O193-3 each contain a pair of E. sibiricus 3St chromosomes carrying leaf rust resistance genes. These findings demonstrate that the E. sibiricus 3St chromosome carries the leaf rust resistance gene and that the O27-2, O27-3, and O193-3 lines can serve as novel germplasm sources for introducing this resistance into wheat breeding programs. This study contributes to broadening the genetic diversity of resistance genes available for combating leaf rust in wheat.

Experimental investigation of progressive collapse resistance of bonded local prestressed concrete frame substructures

Bonded local prestressed concrete (BLPC) frames represent a structural form that combines long spans with prestressing and short spans without prestressing. Progressive collapse has become a focus of research in recent years, given the potential for severe consequences. BLPC frames exhibit distinct progressive collapse resistance compared to symmetrical structures due to their notable asymmetry. Therefore, this paper tested the behavior of two BLPC substructures and one unequal-span reinforced concrete (USRC) substructure against progressive collapse in the middle column removal scenario. The tests were conducted using displacement-controlled static loading, with the loading point situated at the top of the middle column. The test results demonstrate that the BLPC frame employs a two-stage mechanism to resist progressive collapse, comprising the beam-beam stage and the beam-link stage. Additionally, the frame exhibits a tri-fold failure mode. At the location of attachment of the short-span beam to the side column, the top rebars were found to be entirely fractured. At the junction of the reinforced and non-reinforced regions of longitudinal rebar in the long-span beam, a substantial crack developed, extending almost through. This indicates that the plastic hinge of the long-span beam appeared at the location where the longitudinal rebars were changed, rather than at the beam end. This paper also established a refined numerical model of the BLPC substructures based on LS-DYNA, and the modeling method was verified by comparison with the tests.

Comparative genomic analysis reveals distinct virulence and resistance mechanisms in 21 bacterial fish pathogens

The rising bacterial infections threaten world aquaculture and wild fish populations, making it imperative to increase the understanding of the mechanisms of pathogenic virulence and resistance. This study applies comparative genomic analysis to 21 bacterial fish pathogens, using whole-genome sequences from public genomic resources and sophisticated bioinformatics tools for screening of virulence factors, mobile genetic elements, antibiotic resistance genes, anti-phage defense mechanisms and secretory systems. We have seen that the different pathogens depict a wide range of variability regarding virulence and resistance potential, which may be attributed to species-specific adaptation. Notably, Streptococcus agalactiae and Mycobacterium salmoniphilum were found to possess high offensive and defensive virulence potential, but at different regulative controls. We also found diverse secretion systems and intricate mechanisms for antibiotic resistance, which have provided very important insights into how pathogens adapt to their environments. By categorizing functional genes and finding anti-phage systems, our analysis has revealed new insights into the complex interactions among bacterial virulence, resistance, and host defense mechanisms. These findings not only shed new light on the bacterial pathogenesis process in aquaculture but also provide the bases for focused, therapeutically-based strategies and genomic surveillance programs able to improve disease management and sustainability in aquaculture environments.

Differential eco-physiological performance of eight Eucalyptus species grown in Tunisian’s arid regions

Successful production of Eucalyptus in drylands requires a thorough understanding of the mechanisms involved in their tolerance to abiotic stress as well as drought. The present study aimed to investigate the effects of dry conditions on morpho-physiological characteristics of eight 5-year-old Eucalyptus species trees, Eucalyptus camaldulensis Dehn., Eucalyptus gomphocephala DC., Eucalyptus torquata Luehm., Eucalyptus microtheca F.Muell., Eucalyptus occidentalis Endl., Eucalyptus diversifolia Bonpl., Eucalyptus sargentii Maiden., and Eucalyptus torwood (Spontaneous hybrid), grew in the same arid microhabitat (a plot) characterized by poor soil. The experiments were conducted in summer 2022, a year that was characterized by a low rainfall rate. Thus, at regular intervals, several parameters were assessed. Plant water status, leaf water relations, gas exchanges, and chlorophyll fluorescence in relation to trees growth performance and leaf traits. Results revealed a distinct resistance level to aridity for the studied species, trees were able to grow showing a clear inter-specific variability. Regarding all species, E. camaldulensis, exhibited a particular behavior to preserve their internal functionality. It displayed simultaneously a rapid growth performance with an ability to develop thinner leaves and earlier stomatal closure under water deficit. Although, E. microtheca, E. gomphocephala, and E. diversifolia’ growth were low, but trees attempted to maintain a stable inter-dependence functions for survival. For E. occidentalis, E. torquata, E. sargentii, and E. torwood, we suggest that a physiological acclimation took place under severe conditions, they showed convergence responses for many parameters. Their ability to maintain good leaves’ succulence and thickness is clearly attributed to a significant RWC (71.5% to 82.4%) related to important LTD, LDMC, and SLW, enabling trees to have important stomata conductance and maintain respectful growth performance. Overall, this comparative study of multiple Eucalyptus species revealed significant variability in their functional and adaptive responses to water deficiency and dry weather conditions, which aids in selecting species that are more appropriate to arid natural environments.

Effect of high intensity in every set on strength gains in novice lifters: a randomized controlled trial

Background and Study Aim. Effective program design is essential for maximizing adaptation by balancing strength gains, minimizing stress, and enhancing recovery. However, it remains unclear whether training at high intensity in every set is necessary for optimal strength gains. This study compares the effects of two distinct 6-week resistance training programs on maximum strength in novice lifters. Material and Methods. Twenty participants were recruited and randomly assigned to either the traditional strength program (TSP) or the combined strength program (CSP), both periodized to increase the number of sets every 2 weeks over a total of 6 weeks. A two-way ANOVA was used to analyze maximum isometric strength, maximum dynamic strength, and strength ratio differences between groups and over time. Results. The results showed significant increases in maximum isometric knee extension and elbow flexion strength for both the TSP (CI 95% = 55.87-99.92 N and CI 95% = 10.93-26.86 N, respectively) and the CSP (CI 95% = 43.32-111.42 N and CI 95% = 8.54-28.96 N, respectively). Similarly, maximum dynamic knee extension and elbow flexion strength also improved significantly in both programs (knee extension: TSP CI 95% = 8.16-17.24 kg and CSP CI 95% = 9.10-28.32 kg; elbow flexion: TSP CI 95% = 6.74-11.26 kg and CSP CI 95% = 3.05-10.70 kg). Additionally, strength ratios increased significantly in both the TSP (knee extension CI 95% = 0.87-1.36 N/kg and elbow flexion CI 95% = 0.15-0.42 N/kg) and the CSP (knee extension CI 95% = 0.68-1.59 N/kg and elbow flexion CI 95% = 0.14-0.39 N/kg) from baseline. Conclusions. Both training programs led to significant increases in maximum strength metrics. Novice practitioners did not need to train at high intensity in every set to achieve substantial strength gains. This was particularly evident during the early weeks of training, when recovery and adaptation are critical.

Unveiling environmental transmission risks: comparative analysis of azole resistance in Aspergillus fumigatus clinical and environmental isolates from Yunnan, China.

Azole resistance in Aspergillus fumigatus poses a significant clinical challenge globally. Our previous epidemiological analysis revealed a remarkably high frequency (~80%) of azole-resistant A. fumigatus in Yunnan's greenhouse environments, prompting increased local and regional research for targeted control strategies. In this study, we analyzed 94 clinical A. fumigatus isolates from Yunnan, comparing their susceptibility profiles and genotypic characteristics with environmental strains previously isolated. While the overall frequency of azole resistance in clinical isolates was lower than that in environmental samples, a significant prevalence of cross-resistance, with varying resistance patterns based on minimum inhibitory concentration (MIC) levels was observed, which exceeded rates in other regions of China. Specific mutation combinations in the cyp51A gene were linked to elevated MIC values in clinical and/or environmental samples, while some resistant strains with wild-type cyp51A remain unexplained, indicating a need for further investigation into their resistance mechanisms. The differences in unique genetic elements and the distinct genetic differentiation observed between clinical and environmental isolates can be attributed to Yunnan's unique geomorphology and potential genotype importation from other provinces and abroad. Extensive allele exchanges and sharing contributed to the selection of azole-resistant clinical isolates, suggesting a common environmental origin, and the transmission routes of local drug-resistant strains cannot be excluded. These findings emphasize the imperative for regional and targeted surveillance to monitor resistance trends and guide effective antifungal therapy, and management strategies to mitigate invasive aspergillosis risk in this region.IMPORTANCEAzole resistance in Aspergillus fumigatus is a major global health concern, with particularly high rates (~80%) observed in Yunnan's greenhouse environments. This study compares azole resistance in 94 clinical isolates from Yunnan with environmental strains, revealing lower clinical resistance but significant cross-resistance and distinct resistance patterns. Specific mutations in the cyp51A gene were associated with elevated minimum inhibitory concentration values, though some resistant strains had wild-type cyp51A, highlighting the need for further research. The unique genetic profiles and potential external genotype influences in Yunnan emphasize the need for targeted regional surveillance. Effective monitoring and control strategies are essential to manage and mitigate the risk of invasive aspergillosis.

Real collapse responses of an RC flat plate structure under extreme overloading condition: Reversing load redistribution

Progressive collapse research of concrete flat plate structures, typically investigated through the alternate path (AP) method with a focus on column failure (removal), has often neglected the facts of real-life collapse events which are caused by slab overloading, leading to initial punching shear failure at slab-column joints. Progressive collapse of the structural systems triggered by slab-column joint failures exhibits distinct failure modes and resistance mechanisms from those triggered by column failures. Building upon our initial tests on the overloaded slab specimen under quasi-static loading regimes, this paper presents an innovative experimental study that closely mirrors the load-resistant mechanisms of the most common collapse incidents in flat plate structure systems in the real world. By successively stacking up gravity loads without additional interventions, the test accurately simulates the spontaneous failure conditions typical of flat plate structures. A key discovery of this research is the identification of a unique reversing load redistribution mechanism, a phenomenon not previously observed in our slab overloading tests or in studies focused on column removal scenarios. This discovery highlights the necessity of enhancing the post-punching capacity at the slab-column joints as a critical factor in preventing collapses due to slab overloading. In addition, this study provides an in-depth examination of the dynamic effects inherent in the progressive collapse of flat plate structures. Evaluating the dynamic increase factor and load amplification factor offers supplementary data pertinent to real-world collapses, providing essential insights for improving the resilience of flat plate structures against initial joint failure due to slab overloading.